Vehicular audio systems may keep passengers awake if they are trying to fall asleep. The driver may be unaware that the passengers are falling asleep, and thus may not turn down the volume of the audio system. There is no known system that informs the infotainment system when an occupant starts to fall asleep.
Another problem is that conversation is difficult within the vehicle while audio is playing too loudly. Often, drivers will manually turn down the volume when trying to have a conversation.